Insulated mugs, glasses, cups and other containers that are adapted to insulate a hot beverage in order reduce heat loss and maintain the temperature of the beverage are well known. Typically, these containers are insulated with a material that is well-suited to reducing heat transfer from the hot beverage. The insulating material is often disposed in a space provided between an outer wall and an inner wall of the container. Some insulated containers can even be microwaved such that the insulating material, and therefore the container itself, can actually be heated. In this way, the heat transfer from the hot beverage to the environment can be reduced, such that the beverage remains warm over a longer period of time.
Vacuum flasks (such as a Thermos®), which have a vacuum chamber disposed between inner and outer walls of the container, are also known which reduce the rate of heat transfer between the ambient environment and the beverage.
Insulated containers are specifically contemplated for holding cold beverages. Such containers can include a heat transfer fluid that is disposed between inner and outer walls of the container. In some instances, the heat transfer fluid can be cooled to a temperature below the freezing point of water when placed in a freezer or other similar apparatus. In this way, when the container is used to hold a cold beverage the heat transfer fluid can absorb heat from the ambient environment and reduce heat transfer from the ambient environment to the cold beverage, keeping the beverage cooler for a longer period.
Insulating fluids of the prior art in general, including U.S. Pat. No. 5,876,620 to Tsai describe a mixture of water and a water absorptive polysodium acrilate in a ratio of 13:1 (cc:g), together with using calcium chloride as a freeze resistance substance and sodium benzoate as a preservative/antiseptic agent. However, as clearly described in Tsai, the fluid is used for cooling mugs only, not suitable for heating and maintaining hot liquids.
There is a distinct lack of containers that are insulated with a material well-suited for reducing heat transfer from a hot beverage and reducing heat absorption by a cold beverage. Accordingly, there is need for a container having an insulative fluid that is well-suited for keeping both cold beverages cool and hot beverages warm.